A molecular systematic overview of wolf spiders associated with Great Artesian Basin springs in South Australia: evolutionary affinities and an assessment of metapopulation structure in two species

Abstract

The molecular genetic techniques of allozyme electrophoresis and mitochondrial DNA sequencing were used to examine species boundaries, phylogenetic affinities, and population structure in wolf spiders associated with artesian springs of the Great Artesian Basin (GAB) in South Australia. These springs contain the only permanent water in this extremely arid region, and consequently are of great biological, economic, and sociological significance. Molecular diagnoses of species boundaries in nine lycosid species, involving 56 individuals genotyped at 37 putative allozyme loci and 21 individuals sequenced for a ~600-bp portion of nicotinamide adenine dinucleotide dehydrogenase 1 (NADH1), were largely concordant with those recently proposed on morphological criteria. They also identified a species not previously collected, and suggested that GAB and mesic forms of Venatrix arenaris (Hogg) may not be conspecific. As well as insights into the evolutionary relationships among species and genera, phylogenetic analysis demonstrated two distinct GAB lineages within Venatrix Roewer and Hogna Simon. Population structure analyses of the two most widespread species revealed contrasting patterns. For V. fontis Framenau & Vink, allozyme analyses of 300 individuals at 15 polymorphic loci plus NADH1 sequence analysis of 72 individuals revealed the presence of distinctive subpopulations at most sites, and a partial correlation with overall geographic proximity. In contrast, allozyme analysis of 191 V. arenaris specimens at 12 polymorphic loci demonstrated a comparative lack of both within-site variability and between-site differentiation in the GAB metapopulation.

Using MODIS Normalized Difference Vegetation Index to monitor seasonal and inter-annual dynamics of wetland vegetation in the Great Artesian Basin: a baseline for assessment of future changes in a unique ecosystem

“…Groundwater from the GAB supports a series of mound spring which contain a number of rare and relic endemic flora and fauna (Fensham and Fairfax 2003;Gotch et al, 2008;Ponder, 2002). The GAB springs are of great national and international importance for their ecological, scientific and economic values, and are culturally significant to indigenous Australians.…”

“…In this study, 8 to 10 years of MODIS NDVI images were used to monitor and quantify vegetation activity and dynamics of the Dalhousie Spring Complex wetlands located on the southwest margin of the Great Artesian Basin (Figure 1a and b). DSC is the most important spring complex in the GAB and discharges 90% of total spring flow in South Australia through 148 separate spring vents (Gotch, 2010). Recent field work (March 2009) increased knowledge about wetland vegetation associated with active Dalhousie springs (White and Lewis, 2010a, b On the basis established, ab indicative of w pixels tested e was applied to Dalhousie Spr 1c) and exclud However, the dynamics of green wetland areas are also controlled by rainfall events on the GAB, natural intra-annual variability of species present within the wetlands, and by historical events at particular sites.…”

The ecology of narrow-range endemic macro-invertebrates of Great Artesian Basin springs

“…In others, they reveal geographically isolated populations whose divergence is generally indicative of species-level splits Murphy et al, 2010;Ponder et al, 1995). The estimates presented here are also underestimates because many taxa await basic investigation (see Appendix 2-3) -algae are largely overlooked (McGregor & Sendall, 2017), as are Acari and other arachnids (Gotch et al, 2008), Ostracoda (De Dekker, 1979), all of which are abundant (Rossini et al, 2015), contain endemics (Furler & Willing, 2006; and are important components of spring ecosystems elsewhere (Cantonati et al, 2012b). There is a great deal of arthropod diversity in other classes and their seasonal semi-aquatic lifecycles make sampling complex (Cantonati et al 2007), though their general propensity for long-distance dispersal may mean few are endemic .…”

“…They generally have the narrowest distributions, and dispersal and environmental limitations combine for many species to restrict them to tiny areas of habitat. They represent a diverse range of unique evolutionary narratives documenting the quaternary changes in our continent, and present examples of evolution in action by epitomising the evolutionary consequences of restrictions on gene flow and environmental forcing for diversification as a process (Colgan & Ponder, 1994, 2000Gotch et al, 2008;Murphy et al, 2009;Murphy et al, 2013;Ponder, 1995;Ponder et al, 1995). Yet, they are least represented in threatened species legislation, and have the highest data deficiency of all taxa in the system.…”

“…They are currently the more common explanation applied when discussing the potential processes that drive patterns of distribution in species endemic to Australian GAB discharge springs. This has resulted in a strong research focus on assessing whether springs species function as metapopulations (Gotch et al, 2008;Tyre et al, 2001), applying metapopulation models to predict distributions (Nicol et al, 2015), and on defining the limits of dispersal limitation using population genetics (Murphy et al, 2010;J. Worthington-Wilmer et al, 2008;Worthington-Wilmer & Wilcox, 2007).…”